Simultaneous Determination of Trace Lead and Chromium in Water Using Laser-Induced Breakdown Spectroscopy and Paper Substrate

Toxic metals such as lead and chromium in aqueous solutions have been analyzed simultaneously by laser-induced breakdown spectroscopy（LIBS）, in which the ordinary printing paper is used as a liquid absorber which was immerged into Pb（NO3）2and Cr（NO3）3aqueous solution to enrich the heavy metals. This method overcomes the drawbacks of splashing and low sensitivity in ordinary LIBS analysis of water, in which a laser beam is directly focused on a liquid surface. A good signal intensity and reproducibility has been demonstrated. The Pb 405.78 nm and Cr 427.48 nm spectral lines are used as the analytical lines. The variation of line intensity with immersion time was investigated. The calibration curve for quantitative measurement of Pb and Cr in water was established, and the detection limits are 0.033 mg/L and 0.026 mg/L respectively,which is about 2-3 orders of magnitude better than that in the ordinary LIBS analysis of heavy metal in solution.

Flammable carbon nanotube transistors on a nitrocellulose paper substrate for transient electronics

Transient electronics represent an emerging class of technology comprising materials that can vanish in a controlled manner in response to stimuli. In contrast to conventional electronic devices that are designed to operate over the longest possible period, transient electronics are defined by operation typically over a short and well-defined period; when no longer needed, transient electronics undergo self-deconstruction and disappear completely. In this work, we demonstrate the fabrication of thermally triggered transient electronic devices based on a paper substrate, specifically, a nitrocellulose paper. Nitrocellulose paper is frequently used in acts of magic because it consists of highly flammable components that are formed by nitratil^g cellulose by exposure to nitric acid. Therefore, a complete and rapid destruction of electronic devices fabricated on nitrocellulose paper is possible without producing any residue （i.e., ash）. The transience rates can be modified by controlling radio frequency signal-induced voltages that are applied to a silver （Ag） resistive heater, which is stamped on the backside of the nitrocellulose paper. The Ag resistive heater was prepared by a simple, low-cost stamping fabrication, which requires no harsh chemicals or complex thermal treatments. For the electronics on the nitrocellulose paper substrate, we employed semiconducting carbon nanotube （CNT） network channels in the transistor for superior electrical and mechanical properties.

Printed unmanned aerial vehicles using paper-based electroactive polymer actuators and organic ion gel transistors

We combined lightweight and mechanically flexible printed transistors and actuators with a paper unmanned aerial vehicle(UAV)glider prototype to demonstrate electrically controlled glide path modification in a lightweight,disposable UAV system.The integration of lightweight and mechanically flexible electronics that is offered by printed electronics is uniquely attractive in this regard because it enables flight control in an inexpensive,disposable,and easily integrated system.Here,we demonstrate electroactive polymer(EAP)actuators that are directly printed into paper that act as steering elements for low cost,lightweight paper UAVs.We drive these actuators by using ion gel-gated organic thin film transistors(OTFTs)that are ideally suited as drive transistors for these actuators in terms of drive current and frequency requirements.By using a printing-based fabrication process on a paper glider,we are able to deliver an attractive path to the realization of inexpensive UAVs for ubiquitous sensing and monitoring flight applications.